The present invention pertains to a machine for the scrubbing of floors including a moving chassis, a floor scrubbing device, in particular a grinding, polishing or scrubbing device, and a vacuum unit, where the floor scrubbing device has at least two rotating scrubbing elements, in particular grinding, polishing or scrubbing elements, of which at least one is adjustable to vary the operating width of the floor scrubbing device, and where the vacuum device is composed of at least one vacuum head located near the floor in the working direction behind the floor scrubbing device, and connected with the adjustable scrubbing element there is an adjustable vacuum element that sends particles located on the floor and/or liquid to the vacuum head so that the operating width of the vacuum device will be adapted automatically to the working width of the floor scrubbing device.
A floor scrubbing machine of this kind is known from U.S. Pat. No. 3,345,671. Now, this known machine is designed as a kind of scrubbing vacuum and polishing machine and has two adjustable plate brushes located in the working direction in front of a fixed plate brush. In case of a narrow working width, the two adjustable brushes will be retracted toward the middle of the machine. In this position they will clean the floor even in the region where the fixed brush is cleaning the floor. Thus the floor will be scoured in the outer regions of the working width of the machine only by one particular brush, whereas in the middle region a double scouring will occur. This will lead to an adverse element formation on the cleaned floor.
Another related type of floor scrubbing machine is known from U.S. Pat. No. 3,866,541. This machine is likewise designed as a scrubber vacuum cleaner and has one adjustable and one fixed plate brush. The problem described above will occur similarly for this machine as well.
One additional floor scrubbing machine with an adjustable working width is known from U.S. Pat. No. 3,277,511. It is designed as a scrubber vacuum cleaner and has a front mounted scrubber head that is formed by the placement of several plate brushes in a line side by side. This elongated scrubber head is pivot mounted to the chassis about a vertical axis so that one of the plate brushes can move along a circular path. Depending on the adjusted position of the scrubber head (transverse or more or less oblique to the working direction) the working width defined by the projection of the scrubber head in the working direction is adjustable. The working width of the vacuum device which is composed of a vacuum strip connected with the vacuum head and positioned in the rear region of the machine, thus can be adapted to the working width of the scrubber device so that a lateral extension, which is pivot mounted to the vacuum element about a vertical axis, will be pivoted out more or less to a significant extent.
The disadvantage of these machines rests particularly in their poor handling ability and in low operating ease. Since the extension of the vacuum element protruding over the working width of the floor scrubbing device can get caught on obstacles, it can damage adjacent articles or itself and result in injury of a user. Furthermore, during the continually changing working width of the scrubber device, for example, due to obstacles in the working area, for example chair legs and similar features, a continual, permanent adaptation of the working width of the vacuum device by hand is very time-consuming. A further disadvantage rests in an unsatisfactory, nonuniform operation. Since, on the one hand, in tight curve motions of the scrubber vacuum cleaner according to U.S. Pat. No. 3,277,511, an area in an inner curve will not be covered by the scrubber device so that this area will remain moist; and on the other hand, the removal of the liquid film in a relatively large region will not be possible, for example, when cleaning the corners of a room when the machine is moved forward up to the wall and is then moved backward away from the wall. The known scrubber vacuum cleaners with variable working width thus are not used in practice. And the same problems exist for other floor scrubbing machines designed according to the same principle, like, e.g., scrubber and polishing machines, regardless of whether liquid or particle-like solids (abrasives) are to be vacuumed up.